Wire suspension-bridge



(NoModL) H. O. GAR K.

WIRE SUSPENSI I DGE. No. 439,741. Patented Nov. 4, 1890.

-45 a brace to the upper cables when the latter UNITED I STATES PATENT OFFICE.

HENRY'OASS OARMAOK, OF EAST PORTLAND, ASSIGNOR ONE-HALF TO GEORGE IIANNIBAL DURHAM, OF PORTLAND, OREGON.

WIRE SUSPENSION-BRIDGE.

SPECIFICATION forming part of Iletters Patent No; 439,741, dated November 4,1890.

Application filed April 21, 1890. Serial No. 348,944- (No model.)

To all whom it may concern:

Be it known that I, HENRY CASS CARMACK,

a citizen of the United States, residing at East Portland, in the county of Multnomah and State of Oregon, have invented a new and useful Improvement in Wire Suspension- Bridges, of which the following is a specification.

My invention relates to suspension-bridges and it consists in various improvements in construction and arrangement, all of which will be fully described in the following specification, reference being had to the accompanying drawings, in which- Figure 1 is a side elevation of my improved bridge, and Fig. 2 is a detail.

My invention relates particularly to bridges of moderate span, to which classthe principle of the suspension-bridge has not heretofore been commonly applied; and its object is to provide a suspension-bridge which is strong and simple in construction, capable of ready erection, and of easy adjustment to take up any inequalityin the lengths of the ropes or difference in the elevations of the two sides of the bridge.

In the drawings, D D are towers or posts, which are erected upon suitable foundations or abutments E E upon the banks of the stream or chasm to be spanned. The posts D D may be of stone, wood, iron, or other material, according to the requirements of the situation. The cables A B O, of wire, rope, chain, or other flexible material, are stretched upon the posts D and fixed at each end to suitable anchorages K. The cables are arranged to rest, respectively, upon bearings upon the upper, middle, and lower parts of the posts or towers. The upper two cables at each side curve downward from their supports on the towers about parallel with each other, while the adjacent lower cable is curved upward and connected suitably with the mid dle cable B, whereby the lower cable acts as are connected. The lower and middle cables may be connected in any suitable mannerfor instance, they may be twisted together.

Thus for this purpose H H are crosses composed of four radiating iron arms. These crosses are preferably made hollow for the insertion of levers to turn them and to hold them against untwisting. It will be obvious, however, that the cross-arms may be made solid and the bar I hollow without departing from the spirit of my invention. After the cables are suspended and anchored I insert one of the crosses H between the middle and lower cables at their middle points, as shown in Fig. 2, and then turn the cross by means of levers inserted in or upon the arms until the cables are twisted about each other for a considerable distance each side of the cross. I prefer to have the cables twisted for from one-half to two-thirds the distance between the towers. After the cables have been twisted to the same extent upon both sides of the bridge, or to diiferent extents, if that be necessary, to bring the twisted portions up to the same level, I insert the rod I into the inwardly-projecting arms of the crosses to hold them permanently in position. I then complete the bridge by connecting the upper cable with the lower ones by means of a system of suspensories and cross-bracing, and hang a suitable floor system to the cables in any desired manner..

It will be evident that the upper cable A is only for the purpose of giving additional strength to the structure, and may be dis- 8o pensed with in certain cases in which great strength is not required.

If it should be desired to raise or lower either or both sides of the bridge at any time, it can be easily done by taking off a few of the flooring-planks and twisting or untwisting the ropes by means of the crosses H.

Without limiting myself to the precise construction shown, I claim-= 1. In a suspension-bridge, the cables B O, partly twisted together, and means for adjusting the twist and for holding them from untwisting, substantially as described.

2. In a suspension-bridge, the cables B O,

partly twisted together, the crosses H for 5 twisting and holding the cables, and the bar I for holding the crosses, substantially as clethe cables B 0 being partly twisted together scribed.

and united to the cable A by suitable suspen- 3. In a suspensiombridge, the cables B O, sories, substantially as described. partly twisted together, the crosses H, having HENRY CASS CARMACK. 5 hollow arms, and the rod I for holding the Witnesses:

crosses, substantially as described.

H. O. STRATTAN, 4. In a suspension-bridge, the cables A B 0, ROBERT G. MORROW. 

